The disclosed embodiments relate to a medical device. Specifically, the disclosed embodiments relate to a catheter that is capable of easily changing a proceeding direction from a major canal (a main branch) to a minor canal (a side branch) at a bifurcation.
When a stenosis site or an occlusion site is formed in a tubular organ such as a blood vessel, a bile duct, a pancreatic duct, or the like, the flow of fluid (e.g., blood, bile (biliary fluid), pancreatic juice, or the like) through the tubular organ becomes restricted. As a method of treating the stenosis site or the occlusion site, a treatment method using a catheter has been widely used.
Generally, the number of bifurcations of the major canal and minor canals of a tubular organ increases toward the end portion of the tubular organ. Accordingly, when a stenosis site or an occlusion site is formed at an end portion of a tubular organ, the catheter must be able to easily change its proceeding direction from a major canal (a main branch) to a minor canal (a side branch) at a bifurcation.
To address the above considerations, a known catheter includes a bend at a distal end of a catheter shaft in which the bend is bent obliquely towards a predetermined direction (see Japanese Patent Application Publication No. 2011-83596, for example). By providing such a bend, the distal end of the catheter can be oriented towards a direction that is offset with respect to a plane of the body portion of the catheter shaft.
However, in the catheter of Japanese Patent Application Publication No. 2011-83596, a braid is embedded into the catheter shaft, and includes a first wire and a second wire woven together and having the same wire diameter. Thus, the tensile strength of the first wire and the second wire are the same. Accordingly, regardless of whether a technician rotates the catheter in the clockwise direction or in the counterclockwise direction, the rotational force (torque) transmitted to the distal end of the catheter is the same. In other words, the rotational force is isotropic. With such a catheter, when the distal end of the catheter fails to enter a minor canal and is caught by a portion around the entrance of the minor canal at a bifurcation, the bend of the catheter shaft cannot be deformed when the technician rotates the catheter because the rotational force is isotropic. Accordingly, the distal end of the catheter cannot be easily inserted into the minor canal, and it takes time to change the proceeding direction of the catheter from the major canal to the minor canal.